Continuous flow endoscopes are frequently used in endoscopic procedures such as hysteroscopy, trans uretheral urologic endoscopic procedures and arthroscopy. Those skilled in the art would know the structural composition of a continuous flow irrigation endoscope. In this application, the term “continuous flow irrigation” means that fluid simultaneously enters and escapes from a tissue cavity via separate entry and exit points, as a result of which positive fluid pressure is created inside the tissue cavity which distends the cavity. A continuous flow irrigation endoscope generally comprises an inner sheath which is placed inside the cylindrical lumen of an outer sheath. The sheaths are hollow cylindrical tubes which have a distal end which enters a tissue cavity, and a proximal end on which an inflow or outflow port is attached for the purpose of instilling or evacuating fluid from the cavity. The irrigation fluid is instilled via an inflow port.
In many prior art systems the instilled fluid travels through the lumen of the inflow sheath and enters the tissue cavity via the distal opening of the inflow sheath. The waste fluid present inside the tissue cavity enters into a potential space present between the outer and the inner sheaths via multiple holes present near the distal end of the outer sheath and this waste fluid is finally evacuated via the outflow port attached at the proximal end of the outer sheath. A fiber optic telescope is placed inside the cylindrical lumen of the inner sheath to view the interior of the tissue cavity. An endoscopic instrument can also be introduced via the lumen of the inner sheath. In this paragraph, the terms “outer sheath” and “inner sheath” refer to hollow cylindrical tubes which participate in maintaining the structural integrity of the endoscope, and such tubes also cannot move relative to each other. Also, the endoscopic instrument frequently moves relative to the outer and the inner sheaths. Various different types of “continuous flow irrigation endoscopes” have been described in U.S. Pat. Nos. 3,835,842; 5,320,091; 5,392,765; 5,807,240; and U.S. Patent Appln. Publ. Nos. 2003/0130565 A1 (Jul. 10, 2003); 2006/0041186 A1 (Feb. 23, 2006); and 2006/0122459 A1 (Jun. 8, 2006).
The arrangement described in the preceding paragraph has two major disadvantages which are negated by the system of the proposed invention. The disadvantages are as follows:
One disadvantage is that detached tissue pieces, larger than a critical size, present in the tissue cavity are unable to pass through the potential space between the outer and the inner sheaths. Thus, in endoscopic procedures the entire endoscope or the “endoscopic instrument” has to be repeatedly removed from the tissue cavity in order to evacuate the detached tissue pieces present inside the tissue cavity, and this increases the risk of complications like perforation, excessive bleeding and also increases the surgical time. As described in EP 0996375, U.S. Pat. No. 7,249,602 and U.S. Patent Appln. Publ. No. 2006/0047185, it may be argued that, instead of one outflow port, two outflow ports be installed via suitable mechanical means at suitable locations in the endoscope, one outflow port for primarily evacuating the waste fluid from the cavity and the other outflow port being meant to primarily evacuate the resected or cut tissue. However, such an arrangement is not desirable since it necessitates the incorporation of two out flow channels instead of one and it also tends to increase the overall weight of the endoscope. The system of the present invention solves all the problems described in this paragraph by utilizing only one single outflow port, attached to a single outflow channel, which serves to evacuate both detached tissue pieces and waste fluid from the tissue cavity in a continuous irrigation manner.
The other disadvantage is that the inner sheath by virtue of occupying additional space reduces the effective lumen diameter of the endoscope which necessitates a reduction in the thickness or size of the “endoscopic instrument” or the telescope or both. The system of the proposed invention reduces the problem mentioned in this paragraph by utilizing only one housing sheath and by utilizing special type of endoscopic instrument which additionally also functions as the sole outflow channel for simultaneously removing waste fluid and detached tissue pieces. In U.S. Pat. No. 6,824,544, waste fluid and tissue pieces are evacuated via an inflow sheath and the tissue is resected by a separate endoscopic instrument, loop, which cannot participate in removal of waste fluid or tissue pieces; both these features being contrary to the principals of the present invention.
Also, unlike U.S. Pat. No. 6,824,544, in the present invention, a single outflow channel (that is suction channel) is not bifurcated at the level of the endoscope and any type of valve, simple or solenoid operated, is not attached to the outflow channel. Also, unlike U.S. Pat. No. 6,824,544, in the present invention, a controller is not used for influencing or regulating the working of the endoscope, for example by way of controlling the opening and closing motion of solenoid valves. This paragraph describes requirements which essentially need to be fulfilled by the system of the present invention. These requirements have been imposed so that the use of the invented endoscope is not restricted to any specific type of fluid management system with a controller, so that only one outflow tube is needed to be connected to the endoscope, such that the endoscope is simple, light and user friendly.
In the present invention, the diameter or area of cross section of the inner lumen of a single outflow port needs to be at least equal to the diameter or area of cross section of the outflow channel, so that detached tissue pieces and waste fluid could be evacuated in the most efficient manner. Thus, in the present invention, unlike in EP 0996375, U.S. Pat. No. 7,249,602 and U.S. Patent Appln. Publ. No. 2006/0047185, a valve is not attached to the outflow channel for controlling the pressure or the fluid flow.
The present invention is essentially a continuous flow irrigation endoscope which cannot function if the single outflow channel is blocked, for example by an opening or closing valve. Thus, in the present invention, unlike in EP 0996375, U.S. Pat. No. 7,249,602 and U.S. Patent Appln. Publ. No. 2006/0047185, an opening or closing valve is not attached to the outflow channel.
The detached tissue pieces, especially the large size ones, can be evacuated by continuous flow irrigation only if the outflow channel and outflow port of the endoscope have a substantially large lumen diameter. But the same could cause the cavity to collapse intermittently during an endoscopic procedure because the “large lumen diameter” would promote the pressurized irrigation to be expelled out of the tissue cavity via a large bore outflow port. Such problem has been solved by attaching a specially designed endoscope to a specially designed fluid management system, the resultant arrangement being the system of the present invention.